parenchyma are the functional parts of an organ in the body. This is in contrast to the stroma, which refers to the structural tissue of organs, namely, the connective tissues.

In cancer, the parenchyma refers to the actual mutant cells of a single lineage, whereas the stroma is the surrounding connective tissue and associated cells that support it

parenchyma of most organs is of ectodermal (brain, skin) or endodermal origin (lungs, gastrointestinal tract, liver, pancreas). The parenchyma of a few organs (spleen, kidneys, heart) is of mesodermal origin. The stroma of all organs is of mesodermal origin.

Laparoscopy (from Greek lapara, "flank or loin", and skopein, "to see, view or examine") is an operation performed in the abdomen or pelvis through small incisions (usually 0.5–1.5 cm) with the aid of a camera. It can either be used to inspect and diagnose a condition or to perform surgery.

Hypoplasia is underdevelopment or incomplete development of a tissue or organ

Hypoplasia is a congenital condition, while hyperplasia generally refers to excessive cell growth later in life. (Atrophy, the wasting away of already existing cells, is technically the direct opposite of both hyperplasia and hypertrophy

The name is derived from the Greek: hypo, meaning low, and plasis, which refers to molding or forming.[2] The adjective form is hypoplastic.

caused when a gap called the choroid fissure between two structures in the eye, which is present early in development in the uterus, fails to close up completely before a child is born

The effects a coloboma has on the vision can be mild or more severe depending on the size and location of the gap. If, for example, only a small part of the iris is missing, vision may be normal, whereas if a large part of the retina or optic nerve is missing, vision may be poor and a large part of the visual field may be missing

fistula (pl. fistulas or fistulae) is an abnormal[1] connection or passageway between two epithelium-lined organs or vessels that normally do not connect. It is generally a disease condition, but a fistula may be surgically created for therapeutic reasons

binding causes the channels to open, which allows sodium (Na+) and calcium (Ca2+) ions to flow into the cell causing the outer segment of the photoreceptor to depolarize. This depolarizing flow of ions is known as the dark current. When the retina of the eye detects light, a reaction known as a phototransduction cascade occurs. It is a signal transduction pathway that leads to the activation of the enzyme phosphodiesterase, which hydrolyzes cGMP into 5’-GMP, decreasing the concentration of cGMP.

over activation of cGMP-dependent CNG channels in photoreceptors can lead to their degeneration.

Retinitis Pigmentosa

genetic disease in which patients suffer degeneration of rod and cone photoreceptors. The loss starts in the patient's peripheral vision and progresses to the central visual field, leaving the patient blind by middle age

Almost all responses to odorants in olfactory sensory neurons (OSNs) are facilitated by CNG channels. When an odorant binds to its specific receptor in the chemosenstive cilia membrane, it activates a G protein, which causes a downstream reaction activating the enzyme adenylyl cyclase (AC). This enzyme is responsible for an increase in cAMP concentration within the OSN. cAMP binds to the CNG channels in the OSN membrane, opening them, and making the cell highly permeable to Ca2+. Calcium ions flow into the cell causing a depolarization.

Many forms of cutaneous and mucosal allergy are mediated for a large part by mast cells; they play a central role in asthma, eczema, itch (from various causes) and allergic rhinitis and allergic conjunctivitis. Antihistamine drugs act by blocking the action of histamine on nerve endings. Cromoglicate-based drugs (sodium cromoglicate, nedocromil) block a calcium channel essential for mast cell degranulation, stabilizing the cell and preventing release of histamine and related mediator